Referencing ALL worksheets

How could I do the following?

I have a workbook with several worksheets. There are going to be new sheets added all the time. I want to be able to reference the maximum value of column G (from within another worksheet) of each & every worksheet within this workbook. I then will need to total all of these max values together.

The other problem I have, is that the naming format of each new sheet will be date based and as such is impossible to factor into the formula.

Therefore is it possible to say "Reference EVERY worksheet within this workbook and give me the max value from within colG of each and add these all together'

May I see a sample of your workbook?